Physics modelling and numerical simulation of beam-ion interaction in HEPS

The beam-ion interaction is one of the potential limitations of beam performance in ultra-low emittance electron rings. The High Energy Photon Source (HEPS), under construction in Beijing, is one example for which the beam-ion effect has to be carefully evaluated. In this paper, we will introduce the beam-ion interaction models applied in HEPS. Based on these models, a new numerical simulation code is developed. Currently, the code includes modules such as ionization, beam-ion interaction, synchrotron radiation damping, quantum excitation, bunch-by-bunch feedback etc. Settings such as weak-strong, strong-strong and arbitrary number of interaction points can be launched in the code. It will be shown that the beam instability excited by the beam-ion interaction can be effectively suppressed by the bunch-by-bunch feedback system.